Alloy impact-tool steel



Patented Oct. 1]., 1927.

PATENT OFFICE.

PERCY A. E. ARMSTRONG, OF NEW YORK, N. Y.

ALLOY IMPACT-TOOL STEEL.

No Drawing.

, Per cent. Tungsten 1 to 2.5 Chromium .75 to 1.75 Silicon .05 to .60 Manganese .05 to .60 Carbon .35 to ..60 Tantalum .05 to .95

2 Ironprincipal part of the remainder.

A typical example of alloy steel in accordance with my invention containsf Per cent. Tungsten 2.25

Chromium 1.25 Silicon .20 Manganese .35 Carbon 42 Tantalum :15 to .35 Ironprincipal part of the remainder.

Sulfur and phosphorus should be kept low, preferably under .03%. Copper up to about .1% and nickel up to about 5% are permissible, but not important.

The somewhat similar steel, covered by my prior U. S. Patent No. 1,468,937 of Sept. 25, 1923, and .containing vanadium instead of tantalum, while very useful, was found to 40 be incapable of being hardened to a sufficiently high degree of hardness to stand up as a cutting tool, unless the steel contained high carbon, around .55%.60%, or, if of lower carbon substantially under .45%, un-

less itwas heated in a carbonizing atmosphere, as is oftenobtained in a forge fire,

and quenched from that heat. In the event of such high carbon being employed the tool was usually too brittle to withstand repeated impacts. With the carbon about 12%.4:5%, the tool was incapable of being hardened to with tand use as a ch eL-withwt the edge Application filed November 14, 1825. Serial No. 69,199.

battering, unless heated in a forge fire (whereby the surface is carbonized) and hardened by being quenched from that heat, and would not harden throughout to any great extent for pieces of large diameter, say 1" round, or over. Therefore, the use of the steel of my prior patent was restricted to chisels or punches which had. a small crosssection at their cutting edge or could be readily carbonized, but such tools, if it were attempted to sharpen them by grinding would become so soft on the cutting edge that they would have to be rehardened to obtain a sufficiently hard cutting edge. With the use of tantalum in place of vanadium, the steel tools can be hardened right through in large cross-sections of an inch or more, the

steel is not dependent upon surface carbonization for hardness, and tools made therefrom can be reground repeatedly without losing their hard cutting edges. Furthermore, hardening can be done in substantially any type of furnace, and the steel is adapted for use for impact and cutting tools generally,

including chisels and punches, but withoutrestriction thereto, and for all uses where harl'dness accompanied by toughness is essentia The new steel containing tantalum if made with high carbon of the order of .60% can be given greater hardness than the steel of the prior patent with like carbon, and this hardness is not accompanied by the brittleness characteristic of the first steel. 1

For hardening the steel may be .heated from any source of heat as a forge, gas, 'or oil flame to about 15001800 F., preferably to about 1650 F., and quenched, preferably in oil.

I prefer to replace vanadium with tantalum, as the vanadiun is an expensive element, and does not impart to the alloy suflicient additional properties to justify going to the expense. Vanadium under 1% can, however, be used if desired, or where vanadium is incidentally present, as, for example, in the remelting of steel vanadium content is often present and can be allowed to remain in the finished analysis.

I claim:

1. Alloy impact tool steel which has toughness with h gh hardne containing tungsten 1%2.5%, chromium .75%1.75%, sili- 1.25%, silicon about 20%, manganese about con .05%-.60%, manganese, .05%-.60%, car- 35%, carbon about .42%, tantalum about bon .35%-.60%, tantalum .05%.95% and .1.5%.35%, and the principal part of the re- 10 the principal part of the remainder iron. mainder iron.

5 2. Alloy impact tool steel which has In testimony whereof, I have signed .my

toughness with high hardness, containing name hereto.

tungsten about 2.25%, chromiumabout PERCY A. E. ARMSTRONG. 

